Pipe coupling with sealing plate

ABSTRACT

A one-piece pipe coupling includes a cylinder with an axial joint and a sealing plate attached in spaced apart relation to the inner surface of the cylinder with a portion of the sealing plate extending beyond the axial joint for sealing the fluid pathways between a leak location and the outer surface of the coupling. A pair of arcuate gaskets extend around and are attached to the inner surface of the cylinder. The sealing plate carries a first sealing pad on the extending portion of its outer surface, which sealing pad includes circumferential guide channels for engaging the arcuate gaskets of the cylinder. The sealing plate also carries a second sealing pad on the other end of its outer surface, which sealing pad attaches the sealing plate in spaced apart relation to the inner surface of the cylinder. Further, the sealing plate carries circumferential sealing pad material on its inner surface to engage the arcuate gaskets attached to the inner surface of the cylinder, thereby forming a sealing connection around the pipe by the arcuate gaskets and the circumferential sealing pad material, and along both of the axial pads.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.07/978,770, filed Nov. 19, 1992, entitled "Pipe coupling with SealingPlate" now issued as U.S. Pat. No. 5,295,716, which is acontinuation-in-part of U.S. application Ser. No. 07/861,940 filed Apr.2, 1992, entitled "Sealing Plate for a Pipe Coupling" now issued as U.S.Pat. No. 5,286,064.

TECHNICAL FIELD

The present invention relates to couplings for sealing leak locations inpipes and pipelines including joints between adjacent pipe ends, andparticularly relates to a pipe coupling with a sealing plate for use insealing the axial joint of the pipe coupling.

BACKGROUND OF THE INVENTION

The sealing of pipe joints and other leak locations in pipes andpipelines is a critical concern, and proper sealing has become moreimportant as efforts have increased to protect the environment. Liquidchemicals, sewage, toxic gases, and other fluid-like materials such asfine dust must be conducted through pipelines without leakage of thematerial from the pipeline and without contamination from outside. Toseal pipe joints, pipeline installers typically encircle the joint witha cylindrical coupling consisting of either two semi-cylindrical piecesfastened together to clamp the pipe ends, or a single cylindrical piecehaving an axial slit which allows the coupling to be opened by an amountsufficient to fit over the pipe ends.

Annular gasket members, such as O-rings, may be placed around the pipeends beneath the coupling to block the escape of fluid axially betweenthe coupling and the pipe ends, but it is then necessary to block escapeof fluid outwardly through the axial slit of the coupling. Several priordevices for this purpose have been developed, as described in U.S. Pat.Nos. 4,360,227; 1,607,943; 2,913,262; 3,153,550; 4,664,428, and5,086,809.

U.S. Pat. No. 4,664,428, which is incorporated herein by reference inits entirety, describes a sealing plate spanning the axial slit of acoupling and contacting two O-rings positioned on opposite sides of thejoint in the pipeline. The sealing plate is positioned outside theO-rings, but between the O-rings and the coupling. The sealing plate hasaxial gaskets along its edges for preventing passage of fluid frombetween the O-rings to the outer surface of the sealing plate. Thissealing plate has the disadvantage, however, that it can only be usedwith continuous annular O-rings which must be properly positioned on thepipe ends before positioning the sealing plate over the O-rings and thenpositioning the coupling over the sealing plate and O-rings. PlacingO-rings around pipe ends may be difficult if there is insufficient roomto maneuver the O-rings onto the pipe ends. Another disadvantage is thatcouplings having arcuate gasket members attached to the inside of thecoupling cannot be used with such a sealing plate. In addition, duringthe positioning and tightening of the coupling, the O-rings may becomemisaligned or the sealing plate may become misaligned with respect tothe O-rings.

U.S. Pat. No. 4,664,428 also describes a sealing gasket extending alongan axial edge of the coupling so that the gasket is positioned betweenthe axial edge and the inner surface of the coupling when the couplingis fixed around the pipe. Both approaches described in U.S. Pat. No.4,664,428 have the disadvantage that in fitting the pipe coupling overthe O-rings and other gaskets, the O-rings may buckle, deform, or bedisplaced, thereby allowing leakage. These problems in installation areparticularly difficult when couplings are being placed underwater bydivers, in confined areas, in open trenches or channels containingflowing water, or on existing pipelines to repair a joint or leak.

Thus, there is a need in the art for a pipe coupling that reliably sealsall fluid paths from the interior of the pipe sections to the exteriorof the pipe coupling. In addition, there is a need for a pipe couplingthat can be installed reliably and conveniently in awkward situations.The inventions in my copending application, Ser. No. 861,940 filed Apr.2, 1992, entitled "Sealing Plate for a Pipe Coupling", have thedisadvantage of a sealing plate which is a separate piece from the pipecoupling. The sealing plate must be placed first in proper positionacross the axial position of the leak location, and then the pipecoupling is closed around a pair of arcuate gaskets so, that the arcuategaskets engage the sealing pads of the sealing plate. Therefore, thereis also a need in the art for a pipe coupling that is of one-piececonstruction and that provides ease of installation as well as sealingconnections.

SUMMARY OF THE INVENTION

The present invention solves the above problems in the art by providinga one-piece pipe coupling. The present invention provides a cylindricalcoupling member, a sealing plate, and gasket segments as a single unit.The present invention is easily installed in a few steps withoutexpensive equipment or a high degree of skill. No separate O-rings needto be installed around the pipe ends.

Generally described, the present invention provides an apparatus forsealing a leak location in a pipe, comprising a cylinder with an innersurface and an outer surface and with an axial joint defined by a firstaxial edge and a second axial edge. The apparatus further comprises asealing plate for preventing passage of fluid to the outer surface ofthe cylinder. The sealing plate is attached to the cylinder in spacedapart relation by an axial sealing pad at the axial joint so that thesealing plate extends outwardly from one of the axial edges of thejoint. Adjacent to the extending axial plate edge, the sealing platecomprises another outer axial sealing pad adhered to the outer surfaceof the plate member. This axial sealing pad in the preferred embodimentdefines a pair of spaced apart circumferential guide channels, one oneach side of the leak location, and a bridging member connecting theguide channels. Further, the sealing plate includes a pair of spacedapart circumferential sealing pads adhering to the inner surface of thesealing plate.

A coupling embodying the present invention also includes a pair ofarcuate gaskets attached to an inner surface of the cylinder. Each ofthe arcuate gaskets extends from the attaching axial sealing pad, aroundthe interior of the cylinder to a position adjacent to the oppositeaxial edge of the joint. When the coupling is closed, the arcuategaskets are positioned against the outer axial sealing pad in the guidechannels, and also against the circumferential sealing pads. The presentinvention further comprises an assembly for closing the pipe couplinginto a closed configuration such that a sealing connection is formedbetween each of the circumferential sealing pads and the correspondingarcuate gasket. The axial joint is sealed without deforming the sealprovided by the arcuate gaskets positioned between the pipe coupling andthe outer surfaces of the pipe.

The present invention also provides a method for sealing a leak locationin a pipe comprising the steps of positioning a pipe coupling such asdescribed above around a leak location and closing the pipe couplingwith a portion of the inner surface of the cylinder and the arcuategaskets engaging the extending axial sealing pad such that a sealingconnection is formed around the pipe by the arcuate gaskets andcorresponding circumferential sealing pads, and along both of the axialpads.

Thus, it is an object of the present invention to provide an improvedone-piece pipe coupling.

It is a further object of the present invention to provide an improvedmethod for sealing a leak location in a pipeline.

It is also an object of the present invention to provide a pipe couplingwith a sealing plate which is easy to position on a pipeline underwater,in confined areas, in open trenches or channels containing flowingwater, or on existing pipelines to repair a joint or leak.

It is yet another object of the present invention to provide an improvedsealing assembly of the axial slit of a cylindrical pipe coupling.

It is also an object of the present invention to provide a means to sealthe axial joint of a pipe coupling without deforming the seal providedby arcuate gaskets positioned between the pipe coupling and the outersurfaces of the pipe.

Other objects, features, and advantages of the present invention willbecome apparent upon review of the following detailed description ofembodiments of the invention, when taken in conjunction with theaccompanying drawing and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial pictorial view of the top of the pipe coupling withsealing plate embodying the present invention.

FIG. 2 is a top pictorial view of the sealing plate of the presentinvention, removed from the coupling.

FIG. 3 is a pictorial view of the pipe coupling showing the interior ofthe sealing plate of FIG. 1.

FIG. 4 is a cross-sectional view of an arcuate gasket used in a pipecoupling embodying the invention.

FIG. 5 is a side cross-sectional view of the pipe coupling with sealingplate of FIG. 1, in a closed position relative to a pipe.

FIG. 6 is a cross-sectional view of the pipe coupling of FIG. 5 takenalong 6--6.

DETAILED DESCRIPTION

Referring now in more detail to the drawings, in which like numeralsrefer to like parts throughout the several views, FIG. 1 is a partialpictorial view of the top of a pipe coupling 10 with sealing plate 11embodying the preferred form of the present invention. Generally, thepreferred embodiment comprises a cylinder 50 and an attached sealingplate 11. The cylinder 50 has at least one axial slit 52 defining afirst axial edge 57a and a second axial edge 57b. Sealing plate 11 isconnected to cylinder 50 in a spaced apart relation to the inner surfaceof the cylinder adjacent to the first axial edge and so that a portionof sealing plate 11 extends beyond the first axial edge 57a toward thesecond axial edge 57b.

Cylinder 50 also includes a pair of upstanding clamping flanges 53a, 53bwhich can be bolted together as shown in FIG. 5 to close the axial slitand thus press the pipe coupling assembly against the outercircumferential surface of a pipe or pipeline. It is often convenient toform the pipe coupling 10 as a pair of semi-circular coupling segments(not shown) so that there are two axial slits requiring two sealingplates 11 to form the pipe joint. Both such joints may be identical tothe joint shown in FIGS. 1, 3, and 5.

FIG. 2 illustrates sealing plate 11 in greater detail. Sealing plate 11includes central plate member 12, preferably made of steel. Therectangular plate member 12 is curved to match the circumference of thepipe or pipeline with which it will be used. The plate member 12 definesa pair of opposing axial plate edges 14a, 14b connected by a pair ofopposing circumferential plate edges 15a, 15b. The plate member 12 hasan outer surface 16 which faces away from the center of the pipelinewhen installed, and an inner surface 17, visible in FIG. 3.

Two generally rectangular axial sealing pads 20, 40 are attached to theouter surface 16 of the plate 12. The first axial sealing pad 20 istriangular in cross section. A broad, elongate face 21 of the triangularpad faces the axial plate edge 14a, and an apex ridge 22 is formed atthe apex of the triangle. Preferably, the first axial sealing pad 20extends beyond the axial edge 14a of the plate 12 to form a skirt 24.The skirt extends down over the axial edge 14a at a shoulder 25 formedin the material of the axial plate sealing pad 20.

In the preferred embodiment, the first axial sealing pad 20 also definesa plurality of approximately cone shaped humps 30a, 30b, 30c, 30d whichextend circumferentially from a point adjacent to the apex ridge 22 downthe broad face 21 and onto the skirt 24, with the base 31 of each coneshaped hump positioned adjacent to the edge of the skirt 24. Two outerhumps 30a, 30d shaped as just described, are positioned a short distanceinwardly from the circumferential edges 15a, 15b. Two inner humps 30b,30c are positioned on the first axial sealing pad 20 a short distanceinwardly from each of the outer humps 30a, 30d. Preferably each pair ofadjacent humps 30a, 30b and 30c, 30d defines a guide channel 34a, 34b,respectively, for receiving an arcuate gasket. The guide channels arespaced apart by the same distance as the arcuate grooves 55a, 55bcarrying arcuate gaskets 60a, 60b of cylinder 50 as described below.

On the first axial sealing pad 20, a bridging member 36 connects theguide channels 34. Thus, in the preferred embodiment, a thick axialridge 36 extends between and connects the inner humps 30b, 30c. Theaxial ridge 36 must be sufficiently high that a coupling installed overthe sealing plate will engage the axial ridge 36 along its entirelength. Preferably, the axial ridge 36 has a pair of extensions 37a,37b, one extending on each end of the axial ridge 36 past the innerhumps 30b, 30c into the guide channels 34. The purpose of the extensions37 is to provide a better engagement between the axial ridge 36a and thearcuate gaskets positioned in the guide channels 34. Those skilled inthe art will understand after reviewing the installation of the sealingplate that the material of the skirt 24 between the inner humps 30b, 30cis not required for the sealing function of the sealing plate 11.

In the preferred embodiment, the second axial sealing pad 40 has agenerally rectangular top surface 41 defining two humps 44a, 44b shapedto be received within the grooves 55a and 55b. Preferably, the secondaxial sealing pad extends beyond the second axial plate edge 14b of theplate. A side 42 of the second axial sealing pad 40 adjacent the secondaxial plate edge 14b is beveled away from the center of the plate.

As noted, the present invention provides the cylinder 50 and sealingplate 11 as a unit. This is accomplished by attaching the sealing platein a spaced apart relation to the cylinder at one of the axial slits. Inthe preferred embodiment, the second axial sealing pad 40 is adhered tothe inner surface of the cylinder along the first axial edge 57a so thatthe sealing plate is connected to the cylinder and a portion of thesealing plate extends beyond the first axial edge to a position spacedoutwardly from the first axial edge. Preferably, the second axialsealing pad 40 is vulcanized to the inner surface of the cylinder. Theattachment of the second sealing pad 40 to the cylinder 50 is furtherdiscussed in connection with FIGS. 4 and 5.

As shown in FIG. 3, a pair of arcuate grooves 55a, 55b are formedpreferably in the inner surface of cylinder 50. In the preferredembodiment, a pair of arcuate gaskets or annular O-ring segments 60a,60b extend around the interior of the cylinder 50 from a positionengaging the sealing plate 11 to a position adjacent to the first axialedge 57a. Preferably, each arcuate gasket 60a, 60b is received andvulcanized into a respective one of the arcuate grooves 55a, 55b. FIG. 4illustrates a preferred cross section for the gasket material used toform the arcuate gaskets 60a, 60b. The gasket defines a rounded side 62extending about 240 degrees around the circumference of the gasketmaterial, with the remaining portion 63 being generally flattened. Aslight ridge 64 extends outwardly along the center of the flattenedportion. The preferred shape as shown in FIG. 4 resembles a medallion orshield. When used as an arcuate gasket in connection with the sealingplate of the present invention, the rounded side 62 is received withinthe guide channels 34 of the first axial sealing pad 20. The ridge 64therefore points outwardly to form a tight seal with the surroundingcoupling. When used to form arcuate gaskets vulcanized to the interiorof the coupling, the flattened portion 63 is received within andvulcanized to the arcuate grooves 55a, 55b of the coupling 50.

Referring again to FIG. 3, the inner surface 17 of plate member 12 ofsealing plate 11 has a pair of spaced apart circumferential sealing pads46a, 46b attached. The two circumferential sealing pads 46a, 46b haveextensions 43a, 43b extending past the axial edge 14b and the secondaxial sealing pad 40, for attachment to both the axial sealing pad 40and the arcuate gaskets 60a, 60b, respectively. An attachment ofextension 43b to arcuate gasket 60a (in phantom) is shown in FIG. 2. Thecircumferential sealing pads 46a, 46b and extensions 43a, 43b are formedby strips of gasket material molded or extruded with an approximatelyhalf-circular central protrusion 47a, 47b at the center of each of thepads 46a, 46b. The central protrusion 47 extends along the length ofeach pad.

FIG. 5 illustrates in cross section the preferred embodiment of thepresent invention. The relative size of the elements is exaggerated inorder to show detail. Pipe coupling 10 is in a closed or clampedposition around a pipe 18. In this position, the first axial plate edge14a of sealing plate 11 is positioned to extend under the first axialedge 57b of cylinder 50 so that an area of overlap 33 is formed.Preferably, overlap 33 is approximately the same size as the area ofoverlap 35 formed as a result of the attachment of the second axialsealing pad 40 to the inner surface of cylinder 50 along second axialedge 53b. In this manner, the pipe coupling 10 is placed over the leaklocation with axial slit 52 positioned over the central area of sealingplate 11.

In other words, the first axial plate edge 14a is positioned adjacent tothe inner surface of the cylinder 50 so that the first axial plate edge14a fits under the arcuate gasket segments 60a, 60b. The arcuate gasketsegments 60a, 60b cross the first axial sealing pad 20 in the guidechannels 34. The sealing plate is positioned directly on the pipe withthe circumferential sealing pads 46, extending parallel and on oppositesides of the leak location. The axial sealing pads 20, 40 extend alongthe pipe line. Referring to FIGS. 1 and 5, when the coupling 50 istightened down against the sealing plate, the arcuate gasket material iscompressed into the guide channels 34 and comes into engagement with thehumps 30. Those skilled in the art will understand that the arcuategasket segments 60 need only extend to a position between the firstsealing pad 20 and the flange 53a. In the preferred embodiment, thearcuate gaskets 60 also engage and compress the extensions 37 of theaxial ridge 36. When fully tightened, the coupling 10 between thearcuate gaskets 60 comes into engagement .with the axial ridge 36. Atthe point where the arcuate gaskets 60 pass over the first axial plateedge 14a of the sealing plate 11, the arcuate gasket 60 are pressedagainst the skin 24, thereby sealingly engaging the arcuate gaskets withthe circumferential sealing pads 46 lying underneath the sealing plate11.

FIG. 5 also illustrates the cross section of the attachment of thesecond axial sealing pad 40 to cylinder 50. The top surface 41 of secondsealing pad 40 is attached to the inner surface of the cylinder alongthe second axial edge 57a by a process of vulcanization. In FIG. 6, itmay be seen that the second sealing pad 40 connects the sealing plate ina spaced apart relation to cylinder 50. As noted, the top surface 41 ofsecond sealing pad 40 is vulcanized to cylinder 50. The second sealingpad is attached to the upper surface 16 of the sealing plate 11. Thepair of circumferential gaskets 46a, 46b are disposed on the underside17 of the sealing plate 11. The circumferential gaskets are alsodisposed on the pipe 18 on either side of the leak location. Thus, thepositioning of the cylinder 50, second sealing pad 40, sealing plate 11and circumferential gaskets 46a, 46b around the pipe seals the axialjoint. The height of the second sealing pad 40 serves to maintain thesecond sealing pad and cylinder in a spaced apart connection so that thedistance between the cylinder and the pipe is uniform around thecircumference of the pipe. Maintaining uniformity of spacing preventsuneven pressure on the arcuate gaskets and avoids deforming the sealprovided.

In addition, the second axial gasket 40 is attached to each of thearcuate gaskets 60a, 60b. FIG. 5 illustrates that in the preferredembodiment the beveled side face 42 of the second axial sealing pad 40is attached preferably in mating engagement to the end 65 of arcuategasket 60a, which is beveled away from its leading edge 66. Further, theunderside 67 of arcuate gasket 60a adjacent its beveled leading edge 66is connected to extension 43b of circumferential sealing pad 46. Thus, asealing connection is made between the arcuate gaskets and the topsurface 16 of sealing plate 11 through the sealing pad 40 as well as thebottom surface 17 through the extensions 43a, 43b.

In contrast to prior sealing plates for this type of application, thesealing plate 11 according to the present invention is effectively underthe arcuate gaskets which surround the leak location. In thisconfiguration, the unitary construction of the pipe coupling providesfor ease of installation. There is no tendency of the arcuate gasketsand the sealing plate to become misaligned with respect to the cylinder50 during the positioning and tightening of the coupling.

Preferably, the arcuate gaskets or gasket segments 60a, 60b are annularO-ring segments. The term O-ring is used herein to include arcuategaskets having various cross sections, with a preferred shape beingshown in FIG. 4. The axial and circumferential sealing pads, as well asO-ring segments and arcuate gaskets described herein, are preferablymade of rubber having a hardness of 40 to 70 Durometer. The axialsealing pads are adhered to the metal plate 12 and to the couplingcylinder 50 preferably by a well known chemical vulcanization process.The axial and circumferential sealing pads are adhered to one anotherand to the arcuate gaskets 60 preferably by a conventional vulcanizationprocess, which may be a heat/pressure vulcanization process.

It may be seen from the foregoing description that a pipe couplingembodying the present invention differs in significant respects fromprior pipe couplings and provides significant advantages. The presentpipe coupling 10 is of one-piece construction with one end of thesealing plate 11 attached in a spaced apart relation to the cylinder 50.The extending end of the sealing plate 11 is placed under the arcuategaskets 60a, 60b so that the circumferential seal is transferred fromthe arcuate gaskets to the circumferential sealing pads 46, while axialridge 36 completes the sealing of the axial slit of the coupling. Whenused with a cylinder having O-ring segments bonded to the interiorthereof, the sealing plate simplifies installation which consists ofplacing the coupling around the pipe with the sealing plate over theleak location, and tightening the coupling. In the preferred embodiment,this process effectively aligns the O-ring segments in the guidechannels of the sealing plate. These advantages greatly facilitateconvenient and accurate installation of pipe couplings, particularly insituations where access to the leak location or joint is difficult andwhere the location is surrounded by water.

While this invention has been described in detail with particularreference to preferred embodiments thereof, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinbefore and as defined in theappended claims.

I claim:
 1. A sealing plate for use with a pipe coupling surrounding aleak location in a pipeline, comprising:a plate having a pair of axialedges along opposite ends of said plate and a pair of side edges alongopposite sides of said plate; a pair of axial sealing pads, one adheredto an outer surface of said plate along each of said axial edges, atleast one of said axial sealing pads defining a pair of spaced apartcircumferential channels therein and a bridging member connecting saidchannels, said bridging member shaped to be engaged by an inner surfaceof said pipe coupling when said inner surface is pressed toward theouter surface of said plate; and circumferential sealing pad materialadhered to an inner surface of said plate and positioned to engage saidpipeline on both sides of said leak location.
 2. The sealing plate ofclaim 1, wherein said one axial sealing pad defining said pair of spacedapart circumferential channels extends beyond at least one of said axialedges at the location of said channels and said circumferential sealingpad material extends beyond said axial edge and is attached to said oneaxial sealing pad.
 3. A pipe joint for sealing a leak location in apipeline, comprising:a sealing plate spanning the axial position of saidleak location and comprising: a plate member having a pair of axialedges along opposite ends of said plate member and a pair of side edgesalong opposite sides of said plate member, a pair of axial sealing pads,one adhered to an outer surface of said plate member along each of saidaxial edges, at least one of said axial sealing pads defining a pair ofspaced apart circumferential channels, one on each side of said leaklocation, said pad extending beyond each of said axial edges at thelocation of said channels; and a bridging member of said pad connectingsaid channels; and circumferential sealing pad material adhered to aninner surface of said plate member and positioned to engage saidpipeline on both sides of said leak location, said circumferentialsealing pad material extending beyond said axial edge and being attachedto said one axial sealing pad; a pair of arcuate gaskets positionedaround said pipeline one on each side of said leak location, each ofsaid arcuate gaskets engaging both of axial sealing pads in respectivechannels; and an annular coupling having at least one axial joint, saidcoupling being positioned around said arcuate gaskets with said axialjoint positioned over said sealing plate, said coupling being closableto engage an inner surface of said coupling with said gaskets and withsaid bridging members, and to engage said circumferential sealing padmaterial with said pipeline.
 4. A pipe coupling for sealing a leaklocation in a pipe, comprising:a cylindrical member having an innersurface and an outer surface, and including an axial joint defined by afirst axial edge and a second axial edge; a sealing plate comprising aplate member having a first axial plate edge and a second axial plateedge along opposite ends of said plate member; a first axial sealing padadhered to an outer surface of said plate member along said first axialplate edge; said sealing plate attached in spaced apart relation to saidinner surface of said cylindrical member adjacent to said first axialjoint edge by a second axial sealing pad adhered to said outer surfaceof said plate member along said second axial plate edge, and with aportion of said sealing plate extending beyond said first axial jointedge of said cylindrical member to a position spaced outwardly from saidfirst axial joint edge; circumferential sealing pad material adhering toan inner surface of said plate member and positioned to engage said pipeon both sides of said leak location; a pair of arcuate gaskets attachedto an inner surface of said cylindrical member, each of said arcuategaskets engaging said second axial sealing pad and said circumferentialsealing pad material, and extending around said cylindrical member to aposition adjacent to said first axial joint edge of said cylindricalmember; and means for closing said pipe coupling with a portion of saidinner surface of said cylindrical member and said arcuate gasketsadjacent said first axial joint edge engaging said first axial sealingpad, sealing connections being formed around said pipe by said arcuategaskets and said circumferential sealing pad material, and along both ofsaid axial sealing pads.
 5. The pipe coupling of claim 4, wherein saidfirst axial sealing pad extends beyond said first axial plate edge atthe location of said channels, and said circumferential sealing padmaterial extends beyond said first axial plate edge and is attached tosaid first axial sealing pad.